In the field of nonwoven materials, there has been a continuing need for materials having a high degree of flexibility and elasticity and which may be manufactured at a low cost. This need has persisted in spite of the fact that such materials could readily be utilized to manufacture a wide variety of garments of both the disposable type, such as disposable diapers, or the nondisposable type, such as pants, dresses, blouses and sporting wear, for example, sweatsuits. Further, such materials could also be utilized in, for example, upholstery, drapery, liner and insulation applications. The traits of flexibility and elasticity are particularly useful characteristics in materials for use in these areas because they permit articles manufactured from such materials to closely conform to the body of the wearer or any item, such as a fixed frame, around which the materials may be wrapped. Additionally, the need for an absorbent nonwoven elastic material has been recognized because such a material could be utilized to manufacture a great disparity of items which have improved absorbency performance as a result of the item's ability to closely conform to a body portion or to some other item which needs to be wrapped in an absorbent material. For example, such a material could be readily utilized in the areas of feminine hygiene or wound dressing.
While the above-discussed combination of characteristics has been a goal of those of skill in the field of nonwoven materials, the prior commercial materials known to us are believed to be lacking or insufficient in one or more of the above-discussed desired characteristics. For example, one group of materials which has been available to those in treating injuries are the so-called "elastic bandages", an example of which is an elastic bandage which is commercially available from the 3M Company of Minneapolis, Minn. under the trade designation "Ace Bandage". Elastic bandages of this type are generally effective in somewhat immobilizing an injured area. However, such elastic bandages generally have a poor ability to absorb bodily fluids exuding from the wound.
Another material for similar uses appears in U.K. Pat. No. 1,575,830 to Johnson and Johnson which relates to flexible and absorbent dressings including diapers, surgical dressings, first aid dressings, catamenial dressings and the like. This patent further appears to relate to dressings which include an absorbent layer laminated to a plastic backing film. The backing film is stated to be elastic and easily stretchable, as well as highly flexible. The elastic backing film may be formed from a blend of materials which contains (a) a major portion of linear or radial A-B-A block copolymers or mixtures of linear or radial A-B-A block copolymers with A-B block copolymers and (b) a resin component. It is stated that the A-blocks of the block copolymers may be derived from styrene or styrene homologs and that the B-blocks may be derived from conjugated dienes or lower alkenes and the resin component may typically include a major portion of a lower molecular weight resin adapted to associate principally with the thermoplastic A-blocks of the block copolymers. It should be noted that this patent deals with an elastic film as opposed to an elastic nonwoven web.
U.S. Pat. No. 4,426,417 to Meitner appears to disclose a matrix of nonwoven fibers which can be used as a wiper with the matrix including a meltblown web having a blend of staple fibers which is a mixture of synthetic and cotton fibers blended therein. The wipers may be formed by a meltblowing process by extruding thermoplastic polymers as filaments into an air stream which draws and attenuates the filaments into fine fibers of an average diameter of up to about ten microns. The staple fiber mixture of synthetic and cotton fibers may be added to the air stream so that the turbulence produced by the air stream results in a uniform integration of the staple fiber mixture into the meltblown web. The meltblown fiber component of the matrix may be formed from any thermoplastic composition capable of extrusion into microfibers. It is stated that examples of such compositions include polyolefins, such as polypropylene and polyethylene, polyesters, such as polyethylene terephthalate, polyamides, such as nylon, as well as copolymers and blends of these and other thermoplastic polymers. The synthetic staple fiber component of the matrix may be selected from the same thermoplastic materials with polyester being preferred. The cotton component includes staple length cotton fibers of average length generally in the range of from about one quarter inch to three quarter inch and denier from about one to one and one half. It is stated that the process for making the material includes compacting the matrix on a forming drum and then directing it over a feed roll and between a patterned roll and an anvil roll where it is pattern bonded. The particular bond pattern is preferably selected to impart favorable textile-like tactile properties while providing strength and durability.
U.S. Pat. No. 4,426,420 to Likhyani appears to disclose a spunlaced fabric which may be made by the hydraulic entanglement of hard fibers (i.e., fibers generally having low stretch characteristics) and potentially elastomeric fibers (fibers capable of elongation by at least one hundred percent before breaking and which are capable of exhibiting elastic characteristics after having been subjected to heat treatment). After hydraulic entanglement of the two types of fibers, the fabric is heat treated to develop the elastic characteristics in the elastomeric fibers. It is stated that the hard fibers may be of any synthetic fiber-forming material, such as polyesters, polyamides, acrylic polymers and copolymers, vinyl polymers, cellulose derivatives, glass, and the like, as well as any natural fiber such as cotton, wool, silk, paper and the like, or a blend of two or more hard fibers. A representative class of potentially elastic fibers is stated to include polyetheresters and more specifically, poly(butylene terephthalate)-co-poly(tetramethyleneoxy) terephthalates.
U.S. Pat. No. 4,100,324 to Anderson et al appears to disclose a nonwoven fabric-like material including an air-formed matrix of thermoplastic polymer microfibers and a multiplicity of individualized wood pulp fibers or staple fibers such as high crimped nylon fibers. It is stated that many useful thermoplastic polymers, polyolefins such as polypropylene and polyethylene, polyamides, polyesters such as polyethylene terephthalate, and thermoplastic elastomers such as polyurethanes are anticipated to find the most widespread use in the preparation of the materials of the U.S. Pat. No. 4,100,324.
U.S. Pat. No. 3,700,545 to Matsui appears to disclose a synthetic multi-segmented fiber which includes at least ten segments composed of at least one component of fiber-forming linear polyamide and polyester extending substantially continuously along the longitudinal direction of the fiber and occupying at least a part of the periphery of the unitary multi-segmented fiber. These fibers may be produced by spinning a multi-segment spinning material having a cross-section of grainy, nebulous or archipelagic structure.
U.S. Pat. No. 3,594,266 to Okazaki appears to disclose melt spinning of a sheath/core bicomponent fiber where one component is a polyamide and the other component is a block-copolyether amide. Okazaki also discusses meltspinning of a sheath/core bicomponent fiber having a first component of a blend of polyamide and a copolyetheramide and a second component of Nylon 6. It is stated that the latter material has 34 percent elongation.